The Microbiology core will be used broadly by all three of the individual project teams. The efficient operations of this central core will be fundamental to the success of this Program Project. The overall Program Project is directed at applying vaginally derived lactobacilli to introduce anti-HIV protein microbicides to mucosal sites within the vagina or rectum as a means of preventing HIV transmission. The Microbiology core has three main objectives. Its first goal is to maintain a library of well characterized vaginal lactobacilli and to continue development of advanced methods to improve genetic manipulation of these microorganisms. These strains and genetic methods will be made available to the various laboratories participating in this Program Project. In particular, this core will undertake an effort to cure a preferred strain of a vaginal Lactobacillus of a resident bacteriophage. In addition, this facitity will pursue the genetic manipulation of a Lactobacillus species that appears to be the dominant colonizer of the vaginal flora of the macaque and humans. While prior attempts to manipulate this species af Lactobacillus have proven difficult, successful engineering of this strain could lead to improved products for testing in the macaque and eventual human clinical use. A second goal, is to refine and optimize processes already operational at Osel for the manufacturing and formulating Lactobacilli. It is desirable to produce formulations of these bacteria that are relatively stable in harsh environments, thus affording widespread use of these lactobacillus-based products. Finally, the Microbiology core will provide encapsulated formulations of genetically modified lactobacilli in support of proposed primate safety, colonization, and efficacy studies, as well as perform a detailed microbiological analysis of samples derived from animals that have received these products.